This present disclosure relates to a system and method for estimating a channel condition based on a filtered pilot energy signal, and more particularly, a system and method capable of improving the stereophonic/monophonic detection of broadcast audio signals.
Receivers that detect stereophonic/monophonic signals are incorporated into a vast number of devices used in everyday life. For example, such receivers are used in automobile radios, a variety of communication systems such as cellular telephones, and even children's toys. Unfortunately, many modern receiver systems suffer from such performance shortfalls as frequent switchover between monophonic and stereophonic modes.
In order to receive FM audio signals, be they music or any other type of information, a receiver must be robust enough to handle changes in the channel wherein the transmission could become very noisy and/or must overcome interference. A pilot tone can be transmitted as part of the baseband signal that is used to modulate an FM carrier signal in order to indicate the nature of the transmission to be stereophonic. The energy of the pilot tone may fluctuate significantly in a harsh channel scenario. Simply comparing the pilot tone energy, estimated at the receiver, against a predetermined threshold may cause the receiver to switch between monophonic and stereophonic mode too frequently and degrade the entertainment quality of the audio program delivered to the consumer.